= Abstract =A human embryo obtained from a salpinx removed for the treatment of tubal gestation was serially sectioned and observed. On gross examination, the embryo showed three prominent pharyngeal arches, but not the cervical sinus. The upper arm bud had just begun to appear with a slight elevation in the skin ectoderm. Both the anterior and posterior neuropores had already been closed. The ...

The Drosophila Malpighian tubule is a model system for studying genetic mechanisms that control epithelial morphogenesis. From a screen of 1800 second chromosome lethal lines, by observing uric acid deposits in unfixed inviable embryos, we identified five previously described genes (barr, fas, flb, raw, and thr) and one novel gene, walrus (wal), that affect Malpighian tubule morphogenesis. Phen...

Anticellular serum inhibited phagocytosis of colloidal gold and staphylococci by HeLa cells. This inhibition of phagocytosis was reversed by conditions which allowed the antibody to elute from the cell. Concentrations of antiserum that inhibited phagocytosis did not interfere with the transport of tritiated thymidine and uridine across the cell membrane, and their incorporation into cell nuclei...

Photoreceptor discs are membrane organelles harboring components of the visual signal transduction pathway. The mechanism by which discs form remains enigmatic and is the subject of a major controversy. Classical studies suggest that discs are formed as serial plasma membrane evaginations, whereas a recent alternative postulates that discs, at least in mammalian rods, are formed through intrace...

The vertebrate eye forms by specification of the retina anlage and subsequent morphogenesis of the optic vesicles, from which the neural retina differentiates. chokh (chk) mutant zebrafish lack eyes from the earliest stages in development. Marker gene analysis indicates that retinal fate is specified normally, but optic vesicle evagination and neuronal differentiation are blocked. We show that ...

The nuclear pore complex (NPC) mediates nucleocytoplasmic transport through the nuclear envelope. How the NPC assembles into this double membrane boundary has remained enigmatic. Here, we captured temporally staged assembly intermediates by correlating live cell imaging with high-resolution electron tomography and super-resolution microscopy. Intermediates were dome-shaped evaginations of the i...

= Abstract =A human embryo considered to belong to stage XV of Streeter's developmental horizon is presented. The embryo was obtained surgically from tubal pregnancy. The crownrump(CR) length was 8.5 rom. A total of 600 serial sections were made through the frontal plane and the following distinguishing features of the key organs were found. There was closure of the lens vesicle, evagination of...